Author

Abstract

Lutzomyia shannoni (Dyar, 1929) (Diptera: Psychodidae) is the only known sand fly vector of vesicular stomatitis virus, a putative leishmaniasis vector, and also boasts the widest distribution of any sand fly in the New World. Research on Lu. shannoni in Central and South America has revealed genetically divergent subpopulations; however, tentative analysis of Lu. shannoni in the U.S. has failed to detect any significant population structure, even between specimens collected from highly disparate localities.

The present study used four molecular markers to more closely investigate the population structure of Lu. shannoni in the U.S., and assess the species’ relationships with specimens from Mexico and Colombia. Phylogenetic networks, population genetics analysis, and phylogenetic tree inference indicated that the U.S. contains a highly homogenous Lu. shannoni population, while Colombia contains several topographicallystructured populations. These analyses also indicated that Lu. shannoni in Mexico represent a genetic intermediary between U.S. and Colombia populations, and indicated a high degree of relatedness between specimens from Mexico and specimens from north- vii western Colombia, implying a northward expansion of the species from South America through Central America via the Isthmus of Panama, and then into the U.S. within recent geologic history. Demographic analysis via Fu’s F-statistics and Bayesian skyline plotting suggested a recent population expansion of Lu. shannoni in the U.S., coinciding with the conclusion of the most recent great glaciation period at the end of the Pleistocene Epoch. Lastly, Maxent models were constructed to assess Lu. shannoni habitat preference and suitability in the U.S. and Colombia, and indicated substantial range tolerance, stymied primarily by cold temperatures, arid climates, and high elevation.